The invention relates to devices for pendent support of piping, and, more particularly, to clevis or yoke-and-saddle type pipe hangers.
Piping installed along ceilings and the like is often supported by a series of pipe hangers. Each hanger is engineered to support a predetermined weight of pipe and contents, and the arrangement of pipe and hangers are specified accordingly, with a built-in safety factor. During installation, the vertical positions of the individual pipe hangers are adjusted to ensure that, at least initially, the weight of the piping is properly distributed, with each pipe hanger bearing its full portion of the load of pipe and contents. Also, in many instances, the piping must be set at a predetermined pitch to facilitate proper drainage or flow.
It is important, for reasons of both safety and operation, that each pipe hanger have the capability to maintain, over time, its portion of the supported piping at the predetermined position and attitude, without shifting or sagging in a manner that would cause other pipe hangers to bear an out-of-limits portion of the load. Others have proposed means for addressing this problem. For example, Hirt U.S. Pat. No. 3,652,045 suggested formation of lugs on the clevis bolt to prevent the upper ends of the arms of the saddle or lower yoke from shifting inwardly thus increasing shear forces inward from the ends of the bolt and causing the hanger to sag.
Often, the concern of preventing sagging of the hanger has been addressed by use of materials that are capable of adequately supporting piping of far greater weight in order to ensure that sagging or other problems will not occur. However, a second, somewhat competing factor is that construction projects often require use of vast numbers of pipe hangers and use of a product over-engineered by even a few cents per unit can represent a significant, unnecessary expense.